A tornado watch is in effect until 8 p.m. Monday in York and Chester counties, as well as 10 other counties in upstate South Carolina.
"A watch is issued when conditions are favorable, for example, either for a severe thunderstorm or tornadoes," AccuWeather.com Senior Meteorologist Dan Kottlowski said. "It doesn't mean severe weather is imminent."
Warnings mean that severe weather is imminent and is based on specific criteria and existing reports received by the NWS.
A tornado watch issued Sunday was later followed by heavy rains and some flooding in parts of York County.
The National Weather Service confirmed that one at least two tornadoes touched down in South Carolina Sunday as a swell of severe weather stretched across the state.
An EF-1 twister touched down along Sunny Plain Road near I-26 in Calhoun County, and an EF-2 hit the Aiken County south of the city of Aiken. EF-1 tornadoes are categorized by having wind speeds of 86 to 110 miles per hour.
Monday’s tornado watch also affects those in Abbeville, Anderson, Cherokee, Greenville, Laurens, Oconee, Pickens, Spartanburg, Union and Greenwood counties.